This invention relates generally to the field of surgical instrumentation and procedure, and more particularly to an improved device and procedure for removing obstructions, usually large particles of food, which have accidentally become lodged in the animal airway to cause choking.
A common cause of choking or obstruction of the human airway is from food or other foreign objects lodged in the back of the throat above or below the epiglottis. If the obstruction is not removed promptly from the airway of the victim, death due to suffocation can occur in a matter of a few minutes.
In common manual emergency techniques, such as back slapping (back blows), chest thrust, or the Heimlich maneuver, the back blows, or the compressions of the chest or the diaphragm, are to cause the pressure inside the lungs to increase to a value greater than the atmospheric pressure which exists above the lodged bolus in the mouth cavity. The difference in pressure between the two sides of the bolus causes an upward force acting on the bolus. This force, if large enough, should overcome the restricting forces that are produced by the throat wall.
Even though these manual techniques have saved many lives, they are not always effective and each one has its deficiencies. For instance, back slapping may further complicate the situation by causing a partial obstruction to become a complete blockage or the Heimlich maneuver, which since 1985 has been recommended by the Surgeon General as the most effective method that should be used on choking victims, if performed incorrectly, may result in fractured ribs or damaged internal organs. Furthermore, the prior art literature indicates that pressure differential created by these methods is on the order of 0.5 psi. This pressure differential is often insufficient for the removal of a tightly lodged object.
In addition to the manual techniques referred to above, a number of mechanical devices for the removal of the lodged bolus from the airway of the choking victim have been patented. In this approach, a pressure difference between the two sides of the bolus is created by lowering the pressure inside the mouth cavity (above the bolus) to a pressure less than the pressure in the lungs. Prior mechanical devices are described in U.S. Pat. Nos. 3,946,736 (Neward), 4,662,367 (Gore), 4,790,818 (DeLuca) and 4,971,053 (Tarrats).
In general, there are at least four conditions that are considered essential to maximize the chance for the successful removal of an obstructing object from the airway of the victim.
1. The upward force created due to the pressure differential across the obstructing object must be large enough to overcome the frictional forces between the object and the area of lodgement.
2. The applied pressure difference should be retained until the object is completely dislodged, i.e. an initial high pressure differential pulse alone may not be sufficient for the removal of the object.
3. The creation of the initial high pressure differential across the object should be sudden and instantaneous, i.e. a gradual build up of the pressure differential is not favored.
4. Since the pressure differential is created by the evacuation of the mouth cavity (mechanical device applications), the device must seal about the mouth and the nostril of the victim.
As mentioned earlier, in the case of the back slapping and Heimlich techniques, the created pressure differential is of the order of 0.5 psi. Furthermore, in these techniques, the duration of the applied pressure differential is relatively short.
Neward""s device, called Throat-E-Vac, comprises a hand operating vacuum pump, a mouthpiece, a hollow tongue depressor, and a nose clamp. This device is capable of creating a high pressure differential and meets conditions 2 and 4, however, it does not meet condition 3, for reason that the creation of the vacuum is gradual instead of being instantaneous.
Gore""s invention comprises a tube-like device that is inserted in the victim""s throat enclosing the larynx area at one end, while the rescuer sucks on the other end in an attempt to remove the lodged bolus. A filter is also provided within the tube to absorb the liquid flowing through the tube. This device poorly meets conditions 1, 2 and 3.
DeLuca""s invention comprises a hollow tongue depressor element, a high pressurized air canister, a manually activated valve and a jet tube orifice placed within an outer tube shell. This device is based on the principle of indirect suction, i.e., by positioning the free end of the tongue depressor in the throat of the victim and opening the valve, a sudden jet of air shoots out from the canister through the jet tube orifice. This jet stream causes a secondary flow through the tube shell resulting in creating a vacuum within the mouth cavity. Even though this device is capable of creating a relatively high pressure differential in a short period of time, it does not meet conditions 2 and 4.
Tarrats"" invention comprises a piston-cylinder mechanism loaded with a spring, a mask and an airway tube which extends from the mask into the victim""s mouth. The principle of operation of this device is very similar to that of Neward""s device, namely, like Neward""s hand-operating vacuum pump, this device also uses a piston and cylinder arrangement for creating of vacuum. Tarrats"" device, however, seems heavier and mechanically more complex and difficult to operate.
Briefly stated, the invention is an apparatus and method for dislodging an article, be it a bolus or other mass, from an animal breathing passage. This apparatus comprises a puncturable, pre-evacuated canister, a release valve, a mask which seals the victim""s oral and nasal cavities, a hollow tongue depressor, the mask being mounted on the tongue depressor and non-collapsible conduit means for connecting the canister and the mask to the release valve.
The method of the subject invention involves instantly exposing the oral cavity through valved conduit means to a vacuum reservoir. This, in contrast to systems wherein a lowered pressure is developed in the oral cavity through a venturi created vacuum or a vacuum pump.
In the method of this invention the free end of the tongue depressor is disposed in the throat of the victim and with the mask in sealing position over the victim""s oral and nasal cavities, the evacuated canister is punctured. The release valve is then opened to thereby communicate the interior of the canister and the oral cavity of the victim to effect an instantaneous vacuum within the oral cavity. The vacuum condition is sustained in the oral cavity until the bolus or other undesired mass is completely dislodged. For the method of this invention, it is not critical that the free end of the tongue depressor be first placed in the mouth of the victim. The order of steps may be reversed and the evacuated canister first punctured and then the tongue depressor placed into the oral cavity with the mask sealing the nasal and oral cavity.
What is important is that the release valve allowing the communication of the oral cavity and the evacuated canister not be opened until the apparatus is placed in a sealing position against the nasal and oral cavities. Moreover, it is important in carrying out the method of the invention that the nasal and oral cavities be effectively sealed in order to maximize the pressure differential on each side of the bolus or lodged object in the throat cavity.
It should also be mentioned that, for many of the above-described prior art systems, the vacuum is created at the site, while, as will be described more fully in the next section, in the invention presented here, the vacuum is brought ready to the site. This not only shortens the operating time, but also eliminates the need for having many of the above-mentioned mechanical parts, such as a piston, cylinder, spring, orifice, hand pump, etc., needed for the creation of the vacuum at the site.